| 摘要 |
In a virtual memory data processing system, the use of a pageable External Page Table data structure for recording current status and disk address information for each virtual page in the system and a non-pageable or pinned table of tables, provides improved system performance when a large number of virtual pages are to be operated on in the same manner. As disclosed, each page of External Page Table entries can record a predetermined number of entries (512), depending on the byte capacity of each virtual page (2,048) and the size of each entry (4 bytes). One page of 512 entries corresponds to 1 megabyte of virtual storage (512 x 2,048) and also appears as one entry in a pinned External Page Table. The pinned External Page Table is referred to as the "XPT of the XPT," and has the same format as the pageable XPT. A 256 megabyte segment of virtual memory is representable in the XPT of the XPT by 256, 4 byte entries, or one-half of a page.
<??>Where all virtual pages represented by a page of XPT entries are to be processed in the same way (i.e., created, destroyed), one operation on one entry in the XPT of the XPT is made, rather than 512 operations on the 512 entries of the XPT.
|
